1. Technical Field
The present invention relates to a liquid crystal device and a projector.
2. Related Art
Protectors are finding increasing home use. The spatial light modulators of projectors are therefore required to provide high-contrast images at low cost, with long life and high light-use efficiency. A typical example of the spatial light modulators is a liquid crystal device. The liquid crystal device has various wires such as data lines, scanning lines, capacitor lines and various electronic elements such as thin-film transistors and thin-film diodes in its image display region. Accordingly, the region of pixels where the light contributing to displaying images can pass through or reflect is restricted by the presence of the wires and electronic elements. The open area ratio of each pixel is defined by the area ratio of each pixel to an area where the light contributing to displaying images can pass through or reflect, that is, an open area. The open area ratio of liquid crystal devices is generally about 70 percent. The light from a light source into the liquid crystal device passes through or reflects by a liquid crystal layer in the state of parallel light rays. Accordingly, when liquid crystal devices are irradiated by parallel light rays, of all light, only an amount of light corresponding to the open area ratio of the pixels is available, and unavailable light becomes a loss.
Therefore, a condenser such as a microlens is generally provided at the opposing substrate of a liquid crystal device, with which the light incident on the liquid crystal device is condensed inside the light-shielding film (the open area of pixels (for example, refer to JP-A-9-127496). The microlens condenses the illumination light from a light source into an open area on a pixel basis. The illumination light condensed by the microlens can efficiently pass through the pixel open area. Accordingly, the use of the microlens array for liquid crystal devices reduces light loss by a light-shielding film, improving light use efficiency.
Such liquid crystal devices are required to have higher definition, higher quality, and higher luminosity. This increases a need for decreasing the pixel pitch. In this case, it is absolutely necessary to optimize the shape of the condenser. For example, JP-A-9-127496 discloses a method for condensing light with an aspheric microlens (in elliptical spherical shape or rotating hyperboloid shape) with a spherical aberration of zero, as mean for improving condensing efficiency. However, examinations by the inventor et al. show that factors of great significance for the condensing efficiency of narrow-pitch liquid crystal devices are control of the distance from the microlens to the light-shielding film as well as the design of the optimum shape of the condenser. For example, thinly etched microlens substrate will be varied in thickness, so that the distance from the microlens to the light-shielding film will also be varied. As a result, the condensing efficiency will also be varied.